(a) Technical Field
Exemplary embodiments of the invention relate to a thin film transistor array panel.
(b) Description of the Related Art
A display device typically includes a thin film transistor provided in each pixel. The thin film transistor defines a switching element using a gate electrode for receiving a switching signal, a source electrode to which a data voltage is applied, and a drain electrode for outputting a data electrode as a three terminal thereof. The thin film transistor may further include an active layer overlapping the gate electrode, the source electrode and the drain electrode. The active layer may include a semiconductor material, e.g., amorphous silicon, and may functions as a channel layer.
In a large-sized display device, a thin film transistor may be driven at a high-speed. In a conventional thin film transistor, where amorphous silicon which is typically used as the active layer, has low electron mobility, and as a result, the high-speed driving may not be effectively performed. Alternatively, thin film transistor may include low-temperature polysilicon and an oxide semiconductor to implement high electron mobility. However, in such a thin film transistor, a processing procedure is typically complicated and uniformity of the semiconductor layer may not be effectively secured.
The thin film transistor may include an oxide semiconductor deposited by a physical vapor deposition (“PVD”) method such as sputtering and evaporation, or an oxide semiconductor including a thin film formed by a coating process or a low-cost printing process. However, in such a thin film transistor array panel including an oxide semiconductor, a change in a carrier concentration may be great based on an effect such as oxygen, water, and oxygen outside the thin film transistor. Further, when the oxide semiconductor is laminated, uniformity of a thickness may be lowered during a solution process, and a characteristic of the thin film transistor may be thereby changed. Accordingly, the characteristic of the thin film transistor may be changed according to a position of the thin film transistor array panel including a plurality of thin film transistors. Further, when the oxide semiconductor is laminated by a PVD method, a density of charges in the semiconductor may be changed based on an amount of oxygen and a thickness of the oxide semiconductor.